Cleaning device having drive means with multiple driving modes

ABSTRACT

A cleaning device ( 10 ) incorporates drive means ( 14 ) and cleaning means ( 20 ), wherein the drive means ( 14 ) are operable to drive the cleaning means ( 20 ) across a surface to be cleaned, and wherein the drive means ( 14 ) are operable to adopt first and second driving modes, the first driving mode being a travelling mode and the second driving mode being a turning mode, wherein locking means ( 40, 42 ) of the drive means ( 14 ) allow selection between the first and second driving modes.

This is an application filed under 35 USC 371 of PCT/GB2005/000343.

This invention relates to a cleaning device, a method of driving acleaning device, a method of cleaning and a drive mechanism for acleaning device.

A number of automatic cleaning devices are known that are used to cleana floor by automatically moving around that floor as a cleaningoperation is undertaken. Some devices operate by mapping out the floorspace of a room to be cleaned by means of complex electronics that storea plan of the room to be cleaned and direct the cleaning device to workaround the planned room. Such complex automatic devices have thedisadvantage of being expensive to manufacture. Also, the devices ofthis type are prone to requiring frequent maintenance and have highpower requirements.

Another type of automatic cleaning device does not incorporate complexelectronic circuitry and takes a random path across a floor surface of aroom to be cleaned with the intention that, by the random nature of thepath, the entire floor surface will at some point have been covered bythe cleaning device. Disadvantages arise with this type of device inthat the random path taken can result in much repetition of the surfacebeing cleaned, unless action is taken to prevent this type of behaviour.

Furthermore, both types of automatic cleaning device have thedisadvantage of becoming stuck in relatively narrow spaces or cornerswithin the room to be cleaned.

It is an object of the present invention to address the above-mentioneddisadvantages. It is a further object to the present invention toprovide a cleaning device having a mode of operation that results in acontrolled random movement across a surface to be cleaned.

According to a first aspect of the invention a cleaning deviceincorporates drive means and cleaning means, wherein the drive means areoperable to drive the cleaning means across a surface to be cleaned, andwherein the drive means are operable to adopt first and second drivingmodes, the first driving mode being a travelling mode and the seconddriving mode being a turning mode, wherein locking means of the drivemeans allow selection between the first and second driving modes.

The drive means may include a rotatably mounted carriage, whichpreferably incorporates at least one drive wheel. The carriage ispreferably mounted to rotate about an axis substantially perpendicularto a rotational axis of the at least one drive wheel. The carriage ispreferably prevented from rotating in the first driving mode. Thecarriage is preferably free to rotate in the second driving mode.

The locking means are preferably operable to be actuated by the cleaningdevice making contact with an obstacle. The locking means are preferablyactuable by an activation element located on a periphery of the cleaningdevice. The activation element may be a bumper, which may protrude fromthe cleaning device. The activation element may be physically,preferably rigidly, linked to the locking means. The activation elementmay be electrically linked to the locking means.

The locking means may be detent means. The detent means may comprise aninterengaging projection/recess pair of the carriage and a body of thecleaning device.

Preferably, the locking means are biased to cause engagement of thefirst driving mode, preferably by a resilient bias. Preferably, theresilient bias is arranged to be overridden by the cleaning devicemaking contact with an obstacle, such as by a physical jolt.

The turning mode may be a manoeuvring mode.

The drive means may provide a rear wheel drive.

According to a second aspect of the invention a method of driving acleaning device comprises adopting one of first and second driving modesof drive means of the cleaning device, wherein the first driving mode isa travelling mode and the second driving mode is a turning mode, andwherein the first and second driving modes are selected by actuation oflocking means of the drive means.

The locking means are preferably actuated by the cleaning device makingcontact with an obstacle, which contact may be an impact.

Actuation of the locking means preferably results in the second drivingmode being adopted. In the absence of actuation of the locking means thefirst driving mode is preferably selected.

Preferably the locking means are biased to lock a carriage of the drivemeans in position in the first driving mode. Preferably an impactbetween the cleaning device and an obstacle causes disengagement of thelocking means.

Selection of the second driving mode preferably allows a carriage of thedrive means to turn about a generally vertical axis. The turning of thecarriage preferably allows the carriage to find a driving direction thatavoids the obstacle that caused the selection of the second drivingmode. The carriage preferably turns to a first direction that at leastone driving wheel of the drive means can drive the cleaning device.

According to a third aspect of the invention a method of cleaning asurface comprises driving a cleaning device across the surface withdrive means, to thereby cause cleaning means of the cleaning device topass over the surface to allow cleaning thereof, wherein the drive meansdrive the cleaning device in a substantially straight path in a firstdriving mode until an obstruction is encountered, whereupon a seconddriving mode is engaged that causes the drive means to turn or reversefrom the obstacle.

The invention extends to cleaning means for a cleaning device asdescribed in the first aspect.

The invention extends to drive means for a cleaning device as describedin the first aspect.

According to a further aspect of the invention a cleaning deviceincorporates drive means for driving the cleaning device across asurface to be cleaned and cleaning means, wherein a front face of thecleaning device is substantially straight and a rear face of thecleaning device is substantially curved, preferably giving the cleaningdevice a general D-shape.

The cleaning means are preferably located substantially adjacent to thefront face on an underside of the cleaning device.

The drive means may be located in a front section of the cleaningdevice, or may be located in a rear section of the device.

All of the features described herein can be combined with any of theabove aspects in any combination.

For a better understanding of the invention, and to show how embodimentsof the same may be carried into effect, reference will now be made, byway of example, to the accompanying diagrammatic drawings in which:

FIG. 1 is a schematic view of an underside of an automatic floorcleaning device;

FIG. 2 is a schematic partial cross-sectional view of a drive mechanismof the floor cleaning device;

FIG. 3 is a partial schematic perspective view of the drive mechanism ofthe floor cleaning device;

FIG. 4 is a schematic perspective view of the floor cleaning device; and

FIG. 5 is a schematic view of an underside of a second embodiment ofcleaning device.

A cleaning device 10 comprises a body section 12, having a drivemechanism 14 with slave wheels 16 and 18, which may be jockey wheels ormay be ball bearings. A cleaning section 20 is located on a base of thebody section 12. The device is shown schematically in FIG. 4.

The cleaning section 20 may be a dry duster pad or it may be a wetcleaning device, which may be fed with cleaning fluid or water from areservoir. The cleaning section 20 may driven in a spinning motion. Thecleaning section 20 is replaceable and or replenishable.

The drive mechanism 14 incorporates wheels 15 joined by axle 22. Theaxle 22 and wheels 15 are held within a carriage 36, from which housinga lower part of each wheel 15 projects. The carriage is on an eccentric,freely rotatable mounting (shown at point 17 in FIG. 1) to allowrotation about a generally vertical axis. The mounting is slightlyforward of the centre of the carriage, so that in forward motion themain portion of the carriage will be dragged behind the eccentricmounting. Internal projections 24 and 26 in the housing 36 provide snapfit retaining clips for the axle 22, said clips allowing free rotationof the axle 22

The axle 22 includes a toothed wheel 28, which engages a toothed wheel30 secured to a drive shaft 32 of a motor 34.

The motor 34 is housed in the body 12 of the cleaning device 10,separate from the carriage 36. The drive shaft 32 extends from the body12 into the carriage 36, as shown in FIG. 2.

As shown in FIG. 3, the carriage 36 incorporates an opening 40 on a rearouter face thereof, which opening 40 is adapted to receive a projection42 of a drive mode selection bracket 44. The drive mode selectionbracket 44 is biased forwards by a spring 46 to urge the projection 42towards the carriage 36 and into the opening 40 in the carriage 36,assuming the carriage 36 is correctly aligned with the projection 42, aswill be described below. The drive mode selection bracket 44 isconnected to a plate 38 which extends horizontally forwards over the topof the carriage 36 to a bumper 48 (see FIG. 1) which projects forwardsout of the body 12 of the cleaning device 10. The bumper 48, the plate38 and drive mode selection bracket 44 are all biased forwards by thespring 46. An opening 50 is provided in the plate 38 to allow the driveshaft 32 to pass between the carriage 36 and the motor 34.

The height of a lower edge of the bumper 48 from the ground is arelevant factor to consider. The height must be sufficiently great thatthe bumper 48 is not triggered by a surface that is only uneven, ratherthan being an obstruction, but the bumper must be sufficiently low thatit does not pass over the top of an obstruction. A clearance of about 3mm has been found to be acceptable. The bumper 48 has an upper edgeextending to the top of the body 12 of the cleaning device 10, so thatthe bumper is triggered in the event that an overhanging obstruction ishit, such as a spar of a chair or the like.

In use, the motor 34 drives the drive shaft 32 causing rotation of thetoothed wheel 30. The toothed wheel 30 rotates about a generallyvertical axis as shown in FIG. 2. Engagement of the toothed wheel 28 andthe toothed wheel 30 converts the vertical rotational axis to agenerally horizontal rotational axis, suitable for driving the wheels15. The toothed wheel 28 is rigidly mounted on the axle 22, meaning thatrotation of the toothed wheel 28 causes rotation of the wheels 15 which,when the cleaning device 10 is placed on a floor, causes the cleaningdevice 10 to be driven forwards, assuming sufficient torque and power isprovided by the motor 34.

In an initial operating condition in the bumper 48, plate 38 and drivemode selection bracket 44 are urged forwards by the spring 36 so thatthe projection 42 engages the opening 40 in the carriage 36. Thecleaning device 10 will be driven in a forwards direction. The carriage36 is freely rotatable on its eccentric mounting about the drive shaft32, but the engagement of the projection 42 and the opening 40 preventrotation of the carriage 36. In this drive mode, the cleaning device isdriven forwards.

Should the cleaning device 10 make contact with an obstacle, such as awall or a piece of furniture, as it is being driven along a floor thebumper 48 will be pushed back slightly towards the body 12 causing theplate 38 and selection bracket 44 move backwards against the bias of thespring 46. This causes the projection 42 to be withdrawn from theopening 40 in the carriage 36.

A feature of the carriage 36 (which as mentioned above is freelyrotatable about the drive shaft 38) is that in the absence of the wheels15 being able to turn because of an obstacle the carriage 36 is causedto rotate in the direction dictated by the rotation of the drive shaft32 until the wheels 15 can turn once more. The reason for rotation ofthe carriage 36 is that the turning force of the power shaft 32 is moreeasily dissipated than it would be if the motor 34 were simply to stall.Thus, the least resistance is typically provided by rotation of thewheel 15.

For example, if the obstruction is a wall forward motion of the cleaningdevice 10 is prevented causing the wheels 15 either to cease rotation orspin without traction. At the same time, with the projection 42 beingremoved from the opening 40 the carriage 36 is allowed to turn inresponse to rotation of the drive shaft 32. Thus, the carriage 36 turnsuntil it can pull the cleaning device 10 in a direction away from oralong an edge of the obstruction, for example to the side. On a normalfloor surface and in the absence of an obstruction the torque of themotor is more easily dissipated by rotation of the wheels 15 than byrotation of the carriage 36. This then results in the cleaning devicemoving in a new direction.

Given the eccentric mounting of the carriage 36, the carriage 36 tendsto assume a forwards direction of movement, because the weight of thecarriage is dragged behind the pivot 17. This leads to realignment ofthe projection 42 with the opening 40. The spring 46 then urges theprojection 42 back into the opening 40 and the carriage 36 is locked inforward drive mode. Thus the cleaning device 10 proceeds until a newobstruction is encountered.

During the period when the projection 42 is disengaged from the opening40 the carriage 36 simply rotates until an orientation is found in whichthe wheels 15 can turn. Thus, the carriage 36 effectively attempts allpossible directions of movement until the first possible direction ofdrive is encountered. The carriage 36 always rotates in the direction ofrotation of the drive shaft 32. Thus, for a clockwise rotation of thedrive shaft, as shown schematically by the arrow in FIG. 3, the carriage36 turns around clockwise to attempt to find a direction of travel tomove away from the obstacle.

It has been found that the cleaning device 10 may perform a three pointturn when encountering an obstacle. If there is friction between thebumper 48 and the obstacle, the first available direction of movementmay be in reverse. If this is the case the cleaning device reverses andafter a short period of travel with the drive mechanism 14 acting in themanner of a rear wheel drive device, the cleaning device turns aroundthrough about 90 degrees and the carriage turns again to resume aforward travel direction.

An alternative embodiment of cleaning device 10 incorporates all of thefeatures of the first embodiment except for the mechanical linkage ofthe bumper 48 through the plate 38 to the drive mode selection bracket44. Instead, a pressure switch or piezo-electric device takes the placeof the bumper 48, which switch or piezoelectric device is electricallyconnected to a solenoid or the like which, when triggered, causes aprojection much the same as that as shown by reference numeral 42 inFIG. 3 to engage the opening 40 in the carriage 36. The projection isbiased forwards to lock the carriage 36 by a spring or the like, asdescribed in relation to the first embodiment. The projection 42 andrecess 40 work in the same way as described above in relation to FIG. 3,except that instead of a mechanical linkage, the linkage is electrical.

As shown in FIG. 1, the plan view of the cleaning device 10 shows thatit has a general D shape, with a curved front face and a generallystraight rear. It has been found that this shape is particularlybeneficial in assisting the cleaning device from freeing itself from anobstruction, such as a wall, more particularly a corner or a obstructioncaused by furniture or other items located on the floor being cleaned.Furthermore, the location of the carriage 36 close to the curved frontface of the cleaning device assists the turning of the cleaning device10 away from an obstruction, in that the curved front face allows thecleaning device to turn more easily away from an obstruction. An angleor corner on the front face may prevent the cleaning device 10 fromrotating with respect to an obstacle.

FIG. 5 shows a different embodiment of cleaning device. All of the partsare common with the embodiment shown in FIGS. 1 to 4, but theorientation of the body section 12 is reversed, so that cleaning device10 has a straight front edge and a curved rear. Also, the drivemechanism 14 is located towards the rear of the cleaning device 10, toprovide a rear wheel drive, compared to the front wheel drive of theembodiment of FIGS. 1 to 4. Instability of the drive mechanism 14 due torear wheel drive does not occur, because the carriage 36 is locked inposition during forward motion, as described above. It has been foundthat better cleaning of an edge of a floor and corners, or aroundobjects, is achieved with a straight front face. The reason for this isthat the flat front face can approach closer to an edge than the curvedface. The same reference numerals are used in FIG. 5 as those in FIGS. 1to 4. The device functions in the same way as the embodiment of FIGS. 1to 4.

The cleaning devices described herein have significant advantagesresulting from the drive carriage 36 being either retained in positionor released depending on a particular drive mode, such as either aforward driving mode or a turning mode. The disadvantages of a poorlyaligned or weighted system in which the cleaning device moves in acurved path is avoided by having the carriage 36 locked in positionuntil an obstruction is encountered. It has been found that a straightpath leads to a floor being cleaned more quickly when compared to acleaning device moving in a tightly curved path.

Furthermore, significant advantages are derived from the shape of thedevice having a front curved edge to assist in a device driving itselfout of or away from obstructions.

Also, the embodiment having a straight front edge has advantages.

The reader's attention is directed to all papers and documents which arefiled concurrently with or previous to this specification in connectionwith this application and which are open to public inspection with thisspecification, and the contents of all such papers and documents areincorporated herein by reference.

All of the features disclosed in this specification (including anyaccompanying claims, abstract and drawings), and/or all of the steps ofany method or process so disclosed, may be combined in any combination,except combinations where at least some of such features and/or stepsare mutually exclusive.

Each feature disclosed in this specification (including any accompanyingclaims, abstract and drawings), may be replaced by alternative featuresserving the same, equivalent or similar purpose, unless expressly statedotherwise. Thus, unless expressly stated otherwise, each featuredisclosed is one example only of a generic series of equivalent orsimilar features.

The invention is not restricted to the details of the foregoingembodiment(s). The invention extends to any novel one, or any novelcombination, of the features disclosed in this specification (includingany accompanying claims, abstract and drawings), or to any novel one, orany novel combination, of the steps of any method or process sodisclosed.

1. A cleaning device comprising drive means and cleaning means, whereinthe drive means are operable to drive the cleaning means across asurface to be cleaned, and wherein the drive means are operable to adoptfirst and second driving modes, the first driving mode being atravelling mode and the second driving mode being a turning mode,wherein locking means of the drive means allow selection between thefirst and second driving modes, and the locking means are operable to beactuated by an activation element located on a periphery of the cleaningdevice making contact with an obstacle, or the locking means of thedrive means are biased to cause engagement of the first driving mode. 2.A cleaning device as claimed in claim 1, in which the drive meansincludes a rotatably mounted carriage incorporating at least one drivewheel.
 3. A cleaning device as claimed in claim 2, in which the carriageis mounted to rotate about an axis substantially perpendicular to arotational axis of the at least one drive wheel.
 4. A cleaning deviceaccording to claim 2 in which the carriage is prevented from rotating inthe first driving mode.
 5. A cleaning device according to claim 2 inwhich the carriage is free to rotate in the second driving mode.
 6. Acleaning device as claimed in claim 1, in which the activation elementis electrically linked to the locking means.
 7. A cleaning deviceaccording to claim 1 in which the locking means are detent means.
 8. Acleaning device as claimed in claim 7, in which the detent meanscomprise an interengaging projection/recess pair of the carriage and abody of the cleaning device.
 9. A cleaning device as claimed in claim 1,in which the bias is arranged to be overridden by the cleaning devicemaking contact with an obstacle.
 10. A cleaning device according toclaim 1 further comprising a front face and a rear face wherein saidfront face of the cleaning device is substantially straight and saidrear face of the cleaning device is substantially curved.
 11. A methodof driving a cleaning device comprises adopting one of first and seconddriving modes of drive means of the cleaning device, wherein the firstdriving mode is a travelling mode and the second driving mode is aturning mode, and wherein the first and second driving modes areselected by actuation of locking means of the drive means and whereinthe locking means are operable to be actuated by an activation elementlocated on a periphery of the cleaning device making contact with anobstacle, or the locking means of the drive means are biased to causeengagement of the first driving mode.
 12. A method as claimed in claim11, in which the locking means are actuated by the cleaning devicemaking contact with an obstacle.
 13. A method according to claim 11 inwhich actuation of the locking means results in the second driving modebeing adopted.
 14. A method according to claim 11 in which, in theabsence of actuation of the locking means, the first driving mode isselected.
 15. A method according to claim 11 in which the locking meansare biased to lock a carriage of the drive means in position in thefirst driving mode.
 16. A method according to claim 11 in whichselection of the second driving mode allows a carriage of the drivemeans to turn about a vertical axis.